Back up the thread and years ago someone said that you should practise at home and perform in public. But there is a point in the practising when you can get things right at home, but the first time you take it out you are much more fluent with the notes.
I don't sing many songs, but the first time I played a tune in a folk club I took the dots along because, although I had memorised it I could only play it slowly if I was trying to remember the next note.

The same goes for calling dances. Some people would say you should never use cards, but there are so many complicated dances that if you are calling at a club both the practise at home to recorded music and the card in your hand (even if you don't look at it, or just glance through before you start) are needed. It gives a wider repertoire and adaptability to the dancers present on that particular night (numbers and expertise)
For a wedding ceilidh memory is sufficient. (With perhaps a list in the mike case)